The invention is related to equipment used for continuously dispensing two or more fluids in a manner suitable for mixing them, which fluids then react to form, for example, a strong adhesive and/or sealant. More particularly, the invention is related to a dispensing apparatus designed to accurately dispense, for purposes of mixing, at least two reactive fluids that may flow at different pressures and/or have different viscosity.
The mixing of two or more fluids, for purposes of activating bonding and/or sealing properties of the mixture, has many applications. Some of these applications, such as bonding tiles or plates to the fuselage of aircraft or other vehicles in a volume manufacturing setting, require that at least two reactive flows be accurately metered and then mixed continuously. The mixture is applied to one or more of the surfaces that are to be bonded or sealed. In such an application, there may be a relatively thick, first fluid which may be referred to as the base material, that is to be mixed with a relatively thin, second fluid which may be referred to as the catalyst. These two disparate fluids are to be accurately and automatically metered and then mixed, continuously, to yield a desired flow amount of a desired mixture.
A dispensing gun can been used to receive accurately metered amounts of two flows, controllably provide the flows to a mixing structure, and then on to the surfaces to be sealed or bonded. See, e.g., U.S. Pat. Nos. 5,477,988 and 5,127,547 to Gerich. The ideal dispensing gun and metering apparatus should be able to provide a continuous flow of a mixture that has the correct proportions of the two reactive fluids, for as many different types of fluid viscosity and flow pressure. In some cases, the gun is purged after each use, so that no residual amounts of the two reactive fluids remain in contact within the gun (thereby making the gun, but not the mixing structure, essentially reusable).